Reflecting only on the details told in the story, consent makes no appearance. Mary is never asked about actions that will impact reproduction, sexuality, or marriage. At best, there is passive acceptance, perhaps filtered through a sense of inequality. You might argue that because men were wrote down the story, it reflected the attitudes toward women, and that some element of consent was not valued by the writers. Unfortunately, that makes the annunciation closer to all those stories in which the gods treat humans as their playthings, including in matters of sexuality and reproduction. In general, the ancient western world made women (to varying degrees) responsible for being raped. A rapist might be punished for a crime against property (due to the financial harm to the family) or a public crime, but not necessarily against the woman. And there were more than a few cases in which a woman was forced to marry her rapist, making the question of consent--such as it was--effectively moot.
